The present invention relates to an apparatus for loading and unloading an aircraft and for ascertaining the weight of the payload.
For an efficient operation of commercial aircraft such as passenger and/or freight aircraft, it is necessary for an optimal planning of any flight that the pilot receives a weight information that is as precise as possible with regard to the payload and also with regard to the load distribution within the aircraft. Such information makes it possible to determine the required fuel quantity for any particular flight much more precisely than is customary heretofore. If no exact data regarding the payload are available, it is necessary to load the aircraft with an additional fuel quantity for safety purposes. Under normal operating conditions such additional fuel quantity is not used up at the end of a flight. The carrying of additional fuel adds to the weight of the aircraft and hence, results in an increased fuel consumption which should be avoided.
It is customary to ascertain the total weight of the freight by weighing the individual freight containers and pallets by means of scales on the ground in an airport. However, such weighing on the ground has certain disadvantages. The weighing stations are not uniformly available at all airports. Further, the passenger weight is only approximated by multiplying an average passenger weight by the number of passengers on any particular flight. Such average weight is not very precise, especially where the average weight employed requires corrections. Besides, the total weight of hand baggage carried by the passengers may also be substantial.
Prior art freight loading and unloading systems have the advantage that they permit the conveying of the individual freight pieces such as containers, pallets, and so forth from the freight gate to the individual loading positions and in the reverse direction by means of roller drives or the like. However, such prior art power driven conveying devices do not provide the possibility of checking the weight of the freight that is being loaded into an aircraft or that has been removed from an aircraft. Thus, heretofore it has not been possible to avoid localized overloading of the freight space structure. It is, however, desirable, that the freight should be distributed substantially uniformly over the available loading space.
A known method of ascertaining the weight of the total payload in an aircraft measures the load that is effective on the landing gear, please see U.S. Pat. No. 3,584,503 issued June 15, 1971. In this method the load applied to each individual landing gear leg is ascertained by measuring a force and then determining the total weight of the aircraft from such measurements. The empty weight of the aircraft and the weight of the fuel is then deducted from the so ascertained total weight to obtain the payload. Such weight ascertaining systems are known as so-called weight and balance systems and are also capable of ascertaining the location of the center of gravity of the aircraft. However, the data representing the payloads are relatively not too precise because they have been ascertained through first measuring the total weight. Besides, such systems are not capable of providing any information regarding the weight of individual load items nor information regarding the weight distribution.